The Stanford Geospatial Network Model of the Roman World (ORBIS) models transportation networks in the Roman World of the 3rd c.:
Spanning one-ninth of the earth’s circumference across three continents, the Roman Empire ruled a quarter of humanity through complex networks of political power, military domination and economic exchange. These extensive connections were sustained by premodern transportation and communication technologies that relied on energy generated by human and animal bodies, winds, and currents.
…
Taking account of seasonal variation and accommodating a wide range of modes and means of transport, ORBIS reveals the true shape of the Roman world and provides a unique resource for our understanding of premodern history.
HT: Mark Hoffman